<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  <style>
    .red{
      color: red;
    }
    .size{
      font-size: 28px;
    }
    .bgc{
      background-color: blanchedalmond;
    }
  </style>
</head>
<body>
  <div id="app">
    <!-- 如何动态绑定类名 -->
    <div class="red" :class="{size:true}">hello</div>
    <div :class="{red:false,size:true}">world</div>
    <div :class="[{red:false},{size:true},{bgc:true}]">hello world</div>
  </div>
  <script>
    new Vue({
      el:'#app',
      data:{

      },
      methods:{

      }
    })
  </script>
</body>
</html>